C++ : OOP 아닌 다른 대안은 없을까?

$ ৬ 001جইࠁӝ 001੄ য۰਍ ੼ٜ 7BMVF0SJFOUFE1SPHSBNNJOHࣗѐ $ ۄ੉࠳۞ܻ
MBHFS৬ JNNFS ࣗѐ

$ ৬ 001جইࠁӝ 001੄ য۰਍ ੼ٜ 7BMVF0SJFOUFE1SPHSBNNJOHࣗѐ MBHFS৬ JNNFS ࣗѐ

؀୓۽ $ ঱য੄ Үਭ਷ 001ѐ֛ਸ ࣗѐೞח Ѫਵ۽ द੘
Үਭ җ੿ীࢲ ੗োझۣѱ $ ঱যܳ 001ߑधਵ۽ ׮ܖח Ѫࠗఠ Үਭ ୡ߈ী ߓ਋ח ղਊਵ۽ DMBTT WJSUVBMఃਕ٘৬ ࢚ࣘী ҙೠ ղਊٜ $ Үਭ੄ द੘

঱যܳ ߓ਋Ҋ पޖীࢲ ੽ೞח ৈ۞ GSBNFXPSL ৉द ؀ࠗ࠙ 001ಁఢ
ӝ߈ .'$ 25 $0. .77. j ੊ࣼೠ ಁఢਸ ߓ਋Ҋ ࢎਊೞҊ ࣄ೐ ъച Ҋ଱ച $ ঱যܳ ࢎਊೞݶࢲ 001੉৻੄ ߑधਸ ځৢܻӝ য۰਑ $ ҃۱੄ द੘ IUUQTMFBSONJDSPTPGUDPNFOVTDQQNGDIJFSBSDIZDIBSU WJFXNTWD 1)

$ ঱যח ׮নೠ ಁ۞׮੐ਸ ૑ਗೞ૑݅ 001 ѐߊ੉ о੢ ؀઺੸
001੄ ౠ૚ ஭ङച࢚ࣘ׮ഋࢿ୶࢚ച ஭ङച ࠂ੟ೠ ղࠗ ࢚కܳ ऀӣ ࢚ࣘ ӝઓ ௿ېझܳ ഛ੢ೞৈ ੤ࢎਊ ׮ഋࢿ ೞա੄ ੋఠಕ੉झ۽ ৈ۞ ӝמਸ ࢎਊ ୶࢚ച ࠂ੟ೠ दझమਸ рױೞѱ ݽ؛݂ 001ࠂणೞӝ

001о ਬܻೠ ѐߊ ࠙ঠо ੓ਸө (6*৬ FWFOUESJWFOQSPHSBNNJOH
ۄ੉࠳۞ܻ ѐߊী ਬܻ അप ࣁ҅ܳ ݽ؛݂ ೞחؘ ਬਊ 001੢੼

೐۽ં౟о ழ૑Ѣա ਬ૑ࠁࣻ ӝр੉ טযզ ࣻ۾ ޙઁо ١੢ೞӝ द੘
r-BSHFTDBMFs001য۰਍ ੼

஭ङച ࠂ੟ೠ ղࠗ ࢚కܳ ऀӣ ௏٘ܳ ੉೧ೞӝ
য۵ѱ ٜ݅ ࣻ ੓਺ ੜ ஭ङച ػ ௏٘ܳ ࢎਊೞח Ѫҗ ѐߊ ߂ ਬ૑ࠁࣻ ೞח Ѫ੄ рӓ 001஭ङച੄ য۰਍ ੼

࢚ࣘ਷ о੢ ъ۱ೠ ழ೒݂ *OIFSJUBODFױ҅о Өয૑Ҋ ѐ߹ ё୓੄
৉ೡ੉ ݽഐ೧ ૑ݶ ഒۆ੉ ழ૗ #BDLUP#BTJDT0CKFDU0SJFOUFE1SPHSBNNJOH +PO,BMC $QQ$PO જ਷ ৘ 001࢚ࣘ੄ য۰਍ ੼

001࢚ࣘਸ য۵ѱ ݅٘ח ৘ class CAnimal { public: virtual void
move() const { ... } virtual ~CAnimal() = default; }; class CBird : public CAnimal { public: void move() const override { … } }; class CMammal : public CAnimal { public: void move() const override { if (isFlyingMammal) { std::cout << "Mammal flies like a bat." << std::endl; } else { std::cout << "Mammal walks." << std::endl; } } void setFlyingMammal(bool canFly) { isFlyingMammal = canFly; } private: bool isFlyingMammal = false; // New requirement forces extra logic into CMammal }; class CFlyingMammal : public CMammal { public: CFlyingMammal() { setFlyingMammal(true); } void move() const override { std::cout << "Flying mammal glides through the air." << std::endl; CMammal::move(); } };

୶࢚ച ػ ё୓ܳ оܻఃח ਊযח ࢎۈ݃׮ ׮ܲ Ѫਸ ځৢܻӝ
ए਑ NFOUBMNPEFM ੉ܴਸ ੜ ૑ਵ۰ח ֢۱੉ ೙ਃ 001୶࢚ച੄ য۰਑ DPOUFYU

௏٘ ੤ࢎਊਸ ਤ೧ ࢚ࣘਸ ഝਊೞҊ ࠗݽ ௿ېझীࢲ ࠙ӝо ࢤӣ
4JOHMFUPOҗ .BOBHFSо ࢤӝӝ द੘ ߄۽ ੉೧غ૑ ঋח ҳઑ NPEFM ٜ੉ ١੢ ୶࢚ച ߂ ੌ߈ചܳ ਤ೧ औѱ ੉೧ೡ ࣻ হѢա ਬ૑ࠁࣻ ೞӝ য۰਍ ӝٜࣿ੉ ੸ਊؽ 001੉࢚җ അप

001ח PCKFDUٜ р੄ rҙ҅sܳ ࢤࢿೣ 0CKFDU ࢎ੉ীࢲ੄ ҙ҅ח
r৊੐sਸ ݅ٚ׮ 4JEFFGGFDU OPOMPDBMSFBTPOJOHߊࢤ <୶ୌ>5POZ7BO&FSE WBMVFPSJFOUFEQSPHSBNNJOHҙ۲ UBMLT 001 য۰਍ ੉ਬח ޖ঺ੌө

001ܳ ੜ ॳח ߑߨٜী ؀ೠ ৈ۞ о੉٘о ੓णפ׮
JTBҙ҅ੌٸ݅ ࢲ࠳ ఋੑੌٸ݅ ࢚ࣘਸ ࢎਊ /POMFBG௿ېझח BCTUSBDUDMBTT۽ ੘ࢿ ࢚ࣘࠁ׮ח DPNQPTJUJPOਸ ࢎਊ $ ঱যীࢲ੄ ب਑DPOTU GJOBM PWFSSJEF QVSFWJSUVBMGVODUJPO 001ੜ ࢎਊೞӝ ਤೠ ֢۱ٜ

WBMVF 0CKFDU *OU MPOH CPoint CWidget ConnectionManager

WBMVF 0CKFDU *NNVUBCMF 1VSFGVODUJPOT GVODUJPOBM .VUBCMF 4JEFFGGFDU 001 3FGFSFODF

ࠛ߸ࢿ JNNVUBCJMJUZ WTо߸ࢿ NVUBCJMJUZ ؀಴੸ੋ ৘ JOU $ķŖŐŕś
WT$ľJEHFU DMBTT ز੘ߑध੄ ର੉ QVSFGVODUJPOWT ࢎ੉٘ ੉ಖ౟ Ӓ ৻ ର੉੼ٜ ध߹ࢿ *EFOUJUZ DPQZز੘ߑध 7BMVF৬ 0CKFDU

ч ઺ब੄ ೐۽Ӓې߁ .VUBCMF0CKFDUࠁױ *NNVUBCMFWBMVFUZQF઺बਵ۽ ѐߊ 5SBOTGPSNBUJPOPGEBUB
OPUNVUBUJPOPGTUBUF *OIFSJUBODFࠁ׮ח DPNQPTJOHࢎਊ 1VSFGVODUJPO TJEFFGGFDUо হח ೣࣻ ੸ӓ ࢎਊ 4UBUF EBUB ৬ CFIBWJPSܳ ܻ࠙ 7BMVFPSJFOUFEQSPHSBNNJOHࣗѐ

WBMVFPSJFOUFE੸ਊ ৘ 1VSFGVODUJPOWTSFGFSFODF // reference void addToVector(std::vector<int>& vec,
int value) { vec.push_back(value); } // Value-oriented std::vector<int> addToVector(const std::vector<int>& vec, int value) { auto result = vec; result.push_back(value); return result; }

WBMVFPSJFOUFE੸ਊ ৘ *NNVUBCMFEBUBTUSVDUVSF // std::string (mutable) std::string s
= "Hello"; s += " World"; // s 를 수정 // immutable string type immutable_string s = "Hello"; auto new_s = s + " World"; // 새로운 string 생성, s는 변하지 않음

WBMVFPSJFOUFE੸ਊ ৘ BDUJPOীࢲ DBMDVMBUJPOਸ ܻ࠙ TJEFFGGFDUܳ ઁѢ //
Not value-oriented void processOrder(Order& order) { double total = calculateTotal(order); order.setTotal(total); sendConfirmationEmail(order); } // Value-oriented struct ProcessedOrder { Order order; double total; }; ProcessedOrder calculateProcessedOrder(const Order& order) { return {order, calculateTotal(order)}; } void handleOrder(const ProcessedOrder& processedOrder) { sendConfirmationEmail(processedOrder); }

WBMVFPSJFOUFE੸ਊ ৘ TUEPQUJPOBM5ա TUEWBSJBOU5ࢎਊ // Not value-oriented bool
parseInteger(const std::string& s, int& result) { try { result = std::stoi(s); return true; } catch (...) { return false; } } // Value-oriented std::optional<int> parseInteger(const std::string& s) { try { return std::stoi(s); } catch (...) { return std::nullopt; } }

1VSFGVODUJPOTOPTJEFFGGFDU -PDBMSFBTPOJOH పझ౟ DPODVSSFODZ 7BMVFPSJFOUFEQSPHSBNNJOH੢੼

TUETPSU TUEGJOE TUEUSBOTGPSNҗ э਷ HFOFSJDBMHPSJUINTWBMVFӝ߈ਵ۽ ز੘ ঌҊ્ܻҗ ؘ੉ఠ੄
ܻ࠙ *UFSBUPS ஶప੉ց੄ TUBUFܳ ׮ܖ૑ ঋ਺ $ ಴ળ ۄ੉࠳۞ܻ৬ 7BMVFPSJFOUFEਗ஗ std::vector<int> input = {1, 2, 3, 4, 5}; std::vector<int> output(input.size()); std::transform(input.begin(), input.end(), output.begin(), [](int i) { return i * i; });

$ ੄ ӝמٜ TUEWBSJBOU TUEPQUJPOBM TUEFYQFDUFE 701ҳഅ ஏݶীࢲ
$ ೖ୊ٜ // Not value-oriented class Shape { public: virtual double area() = 0; }; class Circle : public Shape { double radius; public: double area() override { return 3.14159 * radius * radius; } }; class Rectangle : public Shape { double width, height; public: double area() override { return width * height; } }; // Value-oriented struct Circle { double radius; }; struct Rectangle { double width; double height; }; using Shape = std::variant<Circle, Rectangle>; double area(const Shape& shape) { return std::visit([](const auto& s) { using T = std::decay_t<decltype(s)>; if constexpr (std::is_same_v<T, Circle>) return 3.14159 * s.radius * s.radius; else if constexpr (std::is_same_v<T, Rectangle>) return s.width * s.height; }, shape); }

-BHFS +VBOQF #PM䠃WBS IUUQTHJUIVCDPNBSYJNCPMEJMBHFS 6OJEJSFDUJPOBMEBUBGMPXBSDIJUFDUVSF $
ਸ ਤೠ 3FEVY TUPSFSFEVDFSBDUJPOFGGFDU 701ܳ ਤೠ MJCSBSZࣗѐ MBHFS IUUQTXXXZPVUVCFDPNXBUDI W@P#Y@/C-HI: 2)

4UBUF৬ BMHPSJUIN੄ ܻ࠙ .PEFMTUBUF 3FEVDFSBMHPSJUIN "DUJPOਸ
ా೧ࢲ݅ SFEVDFSഐ୹ 3FEVDFSܳ ా೧ࢲ݅ NPEFMਸ USBOTGPSNBUJPO .PEFM੄ ߸҃ਸ х૑ೡ ࣻ ੓ח ӝמ ઁҕ 701ܳ ਤೠ MJCSBSZࣗѐ MBHFS IUUQTTJOVTPJEFTMBHFSBSDIJUFDUVSFIUNM 3)

struct model { int value = 0; }; struct increment_action
{}; struct decrement_action {}; struct reset_action { int new_value = 0; }; using action = std::variant<increment_action, decrement_action, reset_action>; auto store = lager::make_store<counter::action>( counter::model{}, lager::with_manual_event_loop{}); -BHFS௏٘ ৘ઁ IUUQTTJOVTPJEFTMBHFSBSDIJUFDUVSFIUNM 1)

model update(model c, action action) { return std::visit(lager::visitor{ [&](increment_action) {
++ c.value; return c; }, [&](decrement_action) { -- c.value; return c; }, [&](reset_action a) { c.value = a.new_value; return c; }, }, action); } : : : : : : store.dispatch(increment_action{}); IUUQTTJOVTPJEFTMBHFSBSDIJUFDUVSFIUNM

void draw(counter::model curr) { std::cout << "current value: " <<
curr.value << '\n'; } watch(store, draw); IUUQTTJOVTPJEFTMBHFSBSDIJUFDUVSFIUNM

-BHFSPWFSWJFX

$VSTPSNPEFM੄ XSBQQFS NPEFMDIBOHFEDBMMCBDL [PPNઁҕ -FOTNPEFM ੹୓ীࢲ ੌࠗܳ WJFXTFUೞח
ೣࣻ੄ ૘೤ -BHFS੄ ୶о ӝמٜ struct room{ bool light = false; }; struct house { std::map<string, room> rooms; }; auto store = lager::make_store<house_action>( initial_house, lager::with_manual_event_loop{}); lager::reader<room> kitchen_cursor = store .zoom(lager::lenses::attr(&house::rooms)) .zoom(lager::lenses::at("kitchen")); IUUQTTJOVTPJEFTMBHFSDVSTPSTIUNM 4)

store.dispatch(change_room_action{"kitchen", toogle_light_action{}}); using house_action = std::variant<change_room_action, add_room_action>; house update(house h,
house_action a) { return std::visit(lager::visitor{ [&](change_room_action a) { auto old_room = h.rooms[a.id]; auto new_room = room {!old_room.light_on}; h.rooms[a.id] = new_room; return h; }, [&](add_room_action a) { h.rooms[a.id] = a.r; return h; } }, a); } IUUQTTJOVTPJEFTMBHFSDVSTPSTIUNM

lager::watch(kitchen_cursor, [&](auto changed_room){ // redraw update_view(changed_room); }); IUUQTTJOVTPJEFTMBHFSDVSTPSTIUNM

7BMVFӒܻҊ DPQZ $POUBJOFS੄ DPQZޙઁ $POUBJOFS੄ VQEBUFޙઁ
ബਯ੸ੋ JNNVUBCMFEBUBTUSVDUVSF೙ਃࢿ 7BMVFTFNBOUJDTܳ о۽݄ח Ѫ struct model { std::vector<char> some_huge_vec; }; model update(model m, action a) { auto new_model = model {m. some_huge_vec[a.index]++}; return new_model; }

$ *NNVUBCMFؘ੉ఠ ҳઑ ݽٚ ݫࣗ٘о DPOTU ߸҃غח
൤झషܻܳ ਬ૑ EJGGࣻ೯ оמ ߸҃غ૑ ঋח ؘ੉ఠח ղࠗ ҕਬ DPQZ୭ࣗച *NNVUBCMFEBUBTUSVDUVSF JNNFS const auto v0 = vector<int>{}; const auto v1 = v0.push_back(15); const auto v2 = v1.push_back(16); const auto v3 = v2.set(0, 42); assert(v2.size() == v0.size() + 2); assert(v3[0] - v1[0] == 27); IUUQTTJOVTPJEFTUBMLTJNNFSDQQDPO 5)

TUSVDUVSFTIBSJOH *NNFS੄ ٣੗ੋ ߂ ҳઑ IUUQTQVCMJDTJOVTPJEFTNJTDJNNFSJNNFSJDGQQEG 6)

ബਯ੸ੋ EJGG .PEFM߸҃ ఐ૑ ӝמ struct model { immer::map<int,
string> value; }; model m1 { {1, “1”}}; auto m2 = model{ m1.set(1, “one”) }; auto added = [](auto x){}; auto removed = [](auto x){}; auto changed = [](auto x, auto y){}; immer::diff(m1, m2, added, removed, changed);

-BHFSী ࢎਊغח ݽ؛ਸ JNNFS ۄ੉࠳۞ܻ ࢎਊ೧ࢲ WBMVFఋੑਵ۽ ੘ࢿ -BHFS
*NNFS struct model { immer::box<data> data1; immer::set<int> integers; immer::map<int, string> m; }; auto store = lager::make_store< model >(model{}, lager::with_manual_event_loop{});

model update(model m, action a) { : : : }
lager::watch(cursor, [prev_m = cursor.get()](auto new_m){ immer::diff(new_m, prev_m, [](auto added){ add_item(added); }…); refresh_ui();, });

7BMVFPSJFOUFE1SPHSBNNJOHࣗѐ 001 ߑधਵ۽ ѐߊೞݴ Ҋా߉Ҋ ੓׮ݶ ੌࠗ ੸ਊਸ
Ҋ۰ -BHFS001৬ 701ܳ োѾ೧઱ח ࠳݁૑ *NNFS701੸ਊਸ ذח ۄ੉࠳۞ܻ ݃஖ݴ

ଵҊ ޙ೴ .JDSPTPGU r.'$DMBTTIJFSBSDIZDIBSUs IUUQTMFBSONJDSPTPGUDPNFOVTDQQNGDIJFSBSDIZDIBSU WJFXNTWD $QQ$PO +VBO1FESP#PMJWBS1VFOUFt5IF.PTU7BMVBCMF7BMVFTu
IUUQTXXXZPVUVCFDPNXBUDI W@P#Y@/C-HI: +6"/1&%30#0-䟦7"316&/5& -BHFSEPDT IUUQTTJOVTPJEFTMBHFSBSDIJUFDUVSFIUNM +6"/1&%30#0-䟦7"316&/5& -BHFSEPDT IUUQTTJOVTPJEFTMBHFSDVSTPSTIUNM +6"/1&%30#0-䟦7"316&/5& -BHFSEPDT IUUQTTJOVTPJEFTUBMLTJNNFSDQQDPO +6"/1&%30#0-䟦7"316&/5& ֤ޙ t1FSTJTUFODFGPSUIF.BTTFT33#7FDUPSTJOB4ZTUFNT-BOHVBHFu IUUQTQVCMJDTJOVTPJEFTNJTDJNNFSJNNFSJDGQQEG

C++ : OOP 아닌 다른 대안은 없을까?

C++ : OOP 아닌 다른 대안은 없을까?

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